Roller fountain for liquid transfer in a rotary machine



May 21, 1968 W. R. KING ETAL ROLLER FOUNTAIN FOR LIQUID TRANSFER IN A ROTARY MACHINE Filed NOV. 15, 1965 5 Sheets-Sheet l IN VEN TOR. WILUAM 'R. KiNG. THOMAS W. PANGBURN.

ATTORN EYS May 21, 1968 W. R. KING ETAL.

ROLLER FOUNTAIN FOR LIQUID TRANSFER IN A RO TARY MACHINE 5 Sheets-Sheet 2 Filed Nov. 15, 1965 IN VEN TOR. WILLIAM R. KING. THOMAS W. FANGBURN.

IBY

ATTORNEYS.

y 1968 w. R. KING ETAL 3,384,013

ROLLER FOUNTAIN FOR LIQUID TRANSFER IN A ROTARY MACHINE Filed Nov. 15, 1965 3 Sheets-Sheet 5 IN VEN TOR. WiLLlAM R. KING. THOMAS W. PANGBURN.

BY M M 7 M4 ATTORNEYS.

United States Patent 3,384,013 ROLLER FOUNTAIN FUR LIQUID TRANSFER IN A ROTARY MACHINE William R. King, Blackridge, Wilkinsburg Borough, and Thomas W. Pangburn, Sewickley, Pa, assignors to Jas. H. Matthews & Co., Pittsburgh, Pa, a corporation of Pennsylvania Filed Nov. 15, 1965, Ser. No. 507,738 5 Claims. (Cl. 101-350) ABSTRACT OF THE DISCLOSURE This application discloses an industrial marking machine for applying ink or glue to the side Walls of cartons of the type generally known as vertical printers. The machine comprises, in addition to the vertical printing roll, a vertical inking roll for transferring liquid to the printing roll. The ink is applied to the inking roll by a shoe which bears against the surface of the inking roll and along the face of which is a vertical channel. At the top of the inking roll there is a peristaltic type of pump that continually circulates ink through the channel in the face of the shoe while some of the ink is removed by the inking roll which revolves against the face of the shoe and in front of the channel.

This invention is for an apparatus for use in transfer-ring a liquid, such as ink or adhesive, from a reservoir to a rotating transfer roll from which it is then directly or indirectly applied to an object for its intended purpose.

The invention has primary utility for industrial marking and is especially useful in connection with printing machines designed to apply marking to the vertical side walls of cartons or other objects moving in succession past the printing machine.

Such printing machines are generally referred to in the industrial marking industry as vertical printers, and the invention will be hereinafter particularly described as an inking attachment for vertical printers, but there are many applications where the apparatus of this invention may be most effectively used in horizontal printers, and also it may be used for transferring adhesive to selected areas of cartons or other objects and on either vertical or horizontal surfaces. Specific reference to vertical printers, unless otherwise indicated, is by way of illustration and not as limiting the scope of the invention.

Vertical printing machines used for industrial marking have a printing drum or printing plate holder that is rotated about a vertical axis. As it rotates, it moves against the surface of an inking roll that also revolves about a vertical axis and ink is transferred from the inking roll to the type of the printin plate. At another point in its revolution the printing plate to which the ink has been applied then rolls against the side of a moving carton or other object to be printed upon.

As indicated above, these printers are commonly used in industrial environments on cartons where there may be small fibers or lint-like particles. Conventional inking fountains used in horizontal printers with a dip roll revolving in a trough cannot be used and difiiculty is encountered in keeping the ink distributed uniformly over the surface of the vertical ink roll. Many devices designed for this purpose quickly accumulate these fibers and dust 3,384,fil3 Patented May 21, 1968 particles, and all of them require rather frequent attention, and the ink is not economically employed. Many are adapted only for use with ink of paste-like consistency, and trouble is encountered in starting up after the machine has been idle for several hours.

A primary object of this invention is to provide an attachment for printing, adhesive applying or like machines for transferring a liquid from a reservoir to a revolving roll from which it is in turn applied either directly or usually through an intervening roll, printing plate or the like to an object for its intended purpose, said attachment being of unique construction.

Another object is to provide an inking or like apparatus for printers or other machines having a vertical transfer roll designed to overcome many difficulties inherent in such machines as now generally constructed.

A further object is to provide an inking apparatus or the like for vertical printers and similar machines utilizing a fluid in the nature of ink or adhesive of a more flowable character than is usually possible in machines of this kind, and which will operate for long runs uniformly and with little attention and freedom from failure due to fibers and dust.

A further object is to provide an inking attachment or the like for use interchangeably in either left-hand or right-hand installations, according to the direction in which the cartons move relative to the printing or comparable roll.

The invention as applied to a printer contemplates the combination with a vertical inking roll of a shoe having a concave face conforming to the curvature of the roll and bearing against it throughout substantially its entire length, the shoe being of generally rectangular shape when viewed from the exterior, and means is provided for holding the shoe against the roll.

The shoe has a groove in its concave face extending in a vertical direction and coextensive in an axial direction with the height of the area of the inking roll to which ink is to be applied. Provision is made for introducing ink into the bottom of the groove and removing it from the top, and a compact pump unit operated from the shaft that carries the ink roll constantly circulates ink during the operation of the printer through the groove from a reservoir, and back to the reservoir. Ink in the groove is of course confined by the surface of the roll and the required amount of ink is wiped away by the roll as the roll rotates. Because of this arrangement an ink which is readily flowable liquid may be used and the shoe serves the function of both applying the ink and the function of a doctor blade. Excess ink which may escape and drip in small quantities from the bottom of the inking roll is conducted back to the reservoir. When the apparatus is used with an ink roll revolving in the opposite direction, i.e., changed from a right to a left side or vice versa, the shoe is reversed end for end and the tubing through which ink circulates is shifted to maintain the proper direction of flow.

The invention may be more fully understood by reference to the accompanying drawings, in which:

FIG. 1 is a top plan view of an inking attachment embodying our invention;

FIG. 2 is a vertical section in the plane of line IIIl of FIG. 1;

FIG. 3 is an elevation of the back of the unit with the back plate removed;

FiG. 4 is a top plan view apart from the rest of the apparatus of the reversible top cover plate for the pump;

FIG. 5 is a transverse section in the plane of line V-V of PEG. 1, illustrating the assembly in the area of one of the removable metal elbow connections forming part of the pump;

FIG. 6 is a side elevation of a tube fitting used in the top plate;

FIG. 7 is a schematic diagram from the rear of the shoe showing the tube arrangement for a right-hand" unit; and

FIG. 8 is a similar view showing the transposition of the parts for a left-hand unit.

The printing machine itse is well know the art and the present invention pertains only to the attachment. Consequently only this part of the apparatus is shown.

There is a vertical supporting post 2 on which the entire printing machine is carried, only a portion of the post being shown in the drawings. Parallel with the post there is a support shaft 3. An arm clamped to the post 2 encircles the shaft 3, at 5. Above and below the arm 4 with the shaft-encircling portion 5 are spacing sleeves 6 and 7, res pectively.

The inking device comprises spaced end members in the form of a bottom member preferably in the form of a plate 3, a top member 9, also in the general form of a plate, and a rigid vertical back plate it}. The top and bot tom plates 8 and 9 provide bearings for the opposite ends of a shaft 1} to which the inking roll is keyed. A gear 13 is keyed to the shaft 11 at the top of the inking roll, and a pinion 1- on the support shaft 3 meshes with gear 13 to rotate the ink roll. The printing roll or other workcontacting element to which ink is supplied to be then applied to the cartons, not shown, but the circumference of its circle of revolution which is indicated by dot-anddash line 15 is driven along with the inking device by an intermediate gear 14 commonly used in the art. Shaft 3 is also a pivotal support enabling the inking roll to be swung away from the printing roll.

So far as described, the organization generally differs little from other printing machines of this type.

According to the present invention, ink is applied to and spread over the surface of the inking roll by a shoe designated generally as 16. It is a rectangular block elongated in a vertical direction. It may be formed entirely of meta or plastic, but as here shown it is a metal body 17 with a plastic working face 18 confronting the inking roll. A dense polyurethane plastic as contrasted with formed polyurethane, because of its toughness, wear-resistance and immunity to solvents and chemicals in the ink and to oxida tion has been found particularly adapted to this urpose. The roll-confronting face of the plastic layer is concave in a direction transverse to its vertical axis with its curvature contoured to conform to the surface of the inking roll against which it is pressed.

The contoured working face of the shoe has a verticallyextending groove or channel 19 therein coextensive with the greater portion of its length, terminating, however, short of the top and bottom end portions of the shoe. The width of the shoe is several times the width of the groove 05 that there is a smooth area at each side of the groove. There is a fitting 2% on the side of the shoe that opens through a port 21 into one end of the groove. There is a similar fitting 22 opening through a port 23 into the other end of the groove. Each of these fittings 2t and 22 has a nipple portion onto which a flexible tube or hose is adapted to be fitted, and these nipple portions on the two fittings are turned toward each other.

The shoe is resiliently held against the inking roll by a spring-pressed pin or plunger 24 that enters a recess in the middle of the back of the shoe. The pin projects from a barrel 25 in which the spring (not shown) is confined.

This barrel is exteriorly threaded and is screwed through the back plate 10, so that the pressure of the plunger 75 against the shoe can be adjusted. There is a lock nut 26 on the outer end of the barrel.

This arrangement for supporting the shoe also permits it to be reversed, end for end, so that fitting 20, for example, instead of being on the top right-hand side of the shoe as shown in PEG. 3, is on the bottom left-hand side, and the position of fitting 22 is then similarly reversed.

The top surface of the top plate 9 has a generally circular pump cavity 30 formed therein, and there are two parallel grooves 31 and 32 leading tangentially from this cavity in the same direction and equally spaced from the longitudinal axis of the plate. Each terminates in a vertical opening 33 through the plate inwardly from its rear edge. The top end of the inking roll shaft projects into the pump cavity. This projecting end has a circular cam eccentrically secured to it of smaller diameter than the diameter of the cavity. Surrounding the cam 34 is a ring 34a and an annular series of roller bearings 34b are interposed between the ring and the cam. The pump is a so-called peristaltic pump in which a resilient tube 35 having one end in groove 31 and the other end in groove 32 is looped around the circular wall of the cavity, and the rotation of the cam imparts an oscillatory movement to ring 34a to progressively squeeze the tube, forcing the liquid ahead of it out one tube and drawing liquid as the tube re-cxpands into the tube behind the eccentric cam.

One end of tube 35 is fitted over one leg of a right-angle fitting 36 having one leg thereof in groove 31 and having its other leg extending down through the opening 33. The other end of tube 35 is fitted over the horizontal leg of a similar fitting 37 in the other groove 32. This type of pump is reversible, serving to function whether the cam is retating clockwise or counterclockwise, but depending upon the direction of rotation, one end of the tube is the inlet and the other end is the outlet, and this reverses when the direction of rotation of the cam reverses.

Suspended from the bottom plate 9 is a removable ink reservoir 40 which may be a plastic jar or a metal jar. it is held in place by a bail 41 with a rotatable holding member 42 thereon under the bottom of the vessel for holding the top of the vessel tight in a recess formed in the underside of the bottom plate as best shown in FIG. 2. There are two tubes as and 44 passing through the bottom plate extending into the vessel 43 and terminating near the bottom thereof. Each of these tubes terminates in a nipple portion 43:; and 44a respectively at a level above the bottom plate as best seen in FIG. 3.

In the operation of the inking unit the pump draws ink tom the reservoir upwardly and forces it out and down into the lower end of the shoe. The ink fiows up the groove in the shoe, the ink being confined in the groove by the surface of the inking roll which wipes away some of the ink. The ink which is not carried away by the ink ing roll flows out of the top of the groove and back to the reservoir 4a. In order to be sure that the groove in the shoe is always full of ink, and to insure that when the ma chine is shut down ink will remain in the groove, at least for some period of time, and to assure that there is no appreciable pressure drop in the ink along the length of the groove, it is desirable that the ink always be introduced into the groove at the bottom of the shoe, and that it be carried away from the groove at the top. Since the cccentric cam on the pump reverses the action of the pump when its direction of rotation is reversed, and since the cam will rotate in one direction when the unit is used as left-hand unit, and in the other direction when it is used as a right-hand unit, the tubing to and from the pump and from the pump to the-shoe and the shoe to the reservoir must be arranged according to the direction of ink flow in order that the ink will always enter the groove in the shoe at the bottom of the shoe. This is most conveniently done by reversing the shoe end for end as above suggested when a change in direction of the pump cam is encountered. This is done by backing oil the lock nut 26 on the spring barrel 2-5 and withdrawing the barrel until the shoe may be reversed.

A vertical printer is usually referred to as a righthand printer when, to one standing alongside the conveyor facing toward the discharge end of the conveyor, he sees the printer at his right side of the conveyor, and it is a left-hand printer when the printer is at his lefthand side. In printing machines of this type the drive gear for the printer and inking device is generally tied in by gearing or otherwise to the drive for the conveyor which moves the boxes past the printing machine so that its direction of rotation cannot be arbitrarily changed, and of course the printing plates on the vertical printing drum must roll with the travel of the boxes and not against the travel.

Viewing FIG. 1 of the drawings, the pump cam is indicated as rotating in a clockwise direction. Consequently the end of the pump tube 35 which is in the groove 31 is the discharge tube, and the other end of the intake tube. The periphery of the printing roll designated by the dot-and-dash line in FIG. 1 is therefore revolving in a counterclockwise direction, which means that this printer is a left-hand printer with the boxes moving toward the left as the unit is here viewed. Consequently the printing shoe in FIG. 3 is set for a left-hand printer. There is a tube designated 59 fitted onto the vertical leg of the fitting 36 in the groove 31 at the discharge side of the pump and the other end of this tube is attached to the fitting 22 at the bottom right-hand side of the shoe as shown in FIGS 3 and 8. Another tube 51 is fitted onto the end 43a of the tube 43 and is fitted to the vertical leg of the fitting 37 in the pump grooves 32. Another tube 52 leads from the fitting at the top of the right-hand side of the shoe in FIG. 3 to the top of the tube 44. It returns ink to the reservoir. The circulation of ink is up through the tube 43, its nipple 43a, tube 51, into the pump, and from the pump down through the tube 50 into the lower end of the shoe. Then it flows up through the groove in the shoe and out through the tube 52 to the nipple 44a and tube 44 into the reservoir. This arrangement may be more clearly seen in the schematic view in FIG. 8. If the direction of rotation of the cam is reversed so that the printer becomes a right-hand printer, then tube 50 is connected to nipple 44a at the top of the pipe 44 so that ink is drawn upwardly through the pipe 44 and the tube 50 to the side 31 of the pump which then becomes the intake side. The printing shoe is reversed end for end so that the nipple 20 which is at the top right-hand side in FIG. 3 is at the lower left-hand side as indicated in FIG. 7, and tube 51 is connected to this nipple 20. Tube 52 is connected to the fitting 22 which is then at the top left-hand side of the shoe and to the pipe leading back into the reservoir. This is clearly seen in the schematic view in FIG. 7. Once a printer has been installed it is not frequently necessary to change the tubes, but it is of considerable advantage to the user to be able to change any inking device in his plant from one direction to the other, or to require but one spare instead of one righthand spare and one left-hand spare, or to be able to transfer an inking device from one machine to another without concern as to whether it is going to be used in a left-hand printer or a right-hand printer.

As may be expected, some ink may drop from the inking roll or escape from the lower end of the shoe. Accord ingly the top surface of the bottom plate 8 is countersunk to provide a drainage groove 55 which inclines toward a drain opening 56 through the plate 8 above the jar 40. Ink which escapes from the inking roll in this way is thus collected and returned to the reservoir 40. It will be noted that both tubes 43 and 44 terminate close to but above the bottom of the reservoir 40. With this arrangement, the circulating ink is free of floating fibers and dust that may enter through the drain, and free of heavy sediment, if any, on the bottom. The floating film that collects on top forms a seal to retard evaporation solvent in the ink.

It is from time to time necessary to replace the tube in the peristaltic pump. This may be done by disconmeeting the tubes 50 and 51 and then lifting the respective elbow fittings 36 from the grooves 31 and 32 along with the tube 35 which may then be easily disconnected and replaced with another one. In order to keep the tube 35 in place, together with the fittings 36 and 37, the top of the pump has a cover plate 60 which is preferably made of clear plastic, and which fits tight against the top of the plate 9. It is held in place by several thumb screws 61 which may be easily removed.

There is a stop assembly on the top plate as best seen in FIG. 1. It includes a vertical pin 62 which is screwed into a tapped hole in the top plate 9. Near the base of the pin there is a block 63 from the end of which extends an adjustable stop screw 64. The purpose of the stop screw 64 is to bear against an abutment on the printing roll assembly (not shown) and thereby regulate the pressure with which the printing plate of the printing roll contacts the inking roll. This post 62 not only anchors the block in place, but there is also a tension spring connected at one end to this post and its other end (not shown) is for connection to a corresponding post on the printing unit for exerting a tension tending to pull the printing roll toward theinking roll. This general arrangement is well known in the art, but in the present invention there is a tapped hole 62' at the opposite side of the plate 9 from the one in which the post 62 is entered. When the printer is being used as a left-hand printer, the printing roll (indicated in the dot-and-dash line 15) is then moved to the opposite side of the inking roll so that instead of being above the inking roll in the position shown in FIG. 1, it would appear below the inking roll in a similar view. The terms above and below have significance here simply in connection with the figure of the drawing since the axes of both the printing roll and the inking roll are vertical. When the printing roll is transposed for a left-hand printer, the pin 62 is removed from the position shown in FIG. 1 and the stop assembly is transferred to the opposite side of the top so that the pin 62 is then entered in the opening 62'. The top cover plate 60 is notched out at 65 to clear the stop assembly, and when the stop assembly is shifted in the manner above described, the transparent cover plate is simply turned over side for side so that the notch 65 is then on the lower or op posite side of the plate 9 as viewed in FIG. 1. The holes for the thumb screws are all symmetrical so that the holes for the thumb screws in the transparent plate and the plate 9 will register with either side of the cover tu rned up.

There may be provided on that side of the inking unit facing away from the printing roll a shield to intercept any ink that may be thrown clear of the roll. This, too, is preferably a clear plastic plate. It is indicated in FIG.

I l at 70, and it is held in place by thumb screws 71 which are entered into suitable openings in the sides of the top and bottom plates 8 and 9. When the printer is to be used as a left-hand printer so that the position of the ink roll is then on the side in which the plate 79 is shown in FIG. 1, the thumb screws 71 are removed and the plate 70 is applied to the opposite side of the machine after the printing roll has been shifted to the opposite side of the ink roll.

From the foregoing description it is believed that the operation of the inking device will be quite clear. In assembling the pump, the transparent cover plate is removed and the tube 35 is applied to the elbows 36 and 37 which are then dropped into place in the respective grooves 31 and 32. The tubes 59 and 51 are then connected in the proper manner depending on whether the unit is a right-hand printer or a left-hand printer, i.e., depending on whether the eccentric cam 34 of the pump rotates in a clockwise or counterclockwise direction. If it rotates in the clockwise direction, the tubing is arranged as shown in FIG. 8, and if in a counterclockwise direction, as shown in FIG. 7. As soon as the pump starts to function, which is usually when the conveyor line carrying cartons to be printed upon is started up, the tube leading to the intake side of the pump will draw ink from the reservoir and it will be forced by the pump into the fitting which is then at the bottom of the shoe, filling the groove in the shoe and ultimately the circulation will be complete back to the reservoir. This operation of course is usually started before any articles to be printed upon are actually being moved past the printer. As pointed out above, the machine can be built to the same specifications whether it is a right-hand use or a left-hand use, and the user of the unit can interchange the inking units without difiiculty. Because the ink is kept in constant circulation, a more fluid type of ink can be used than is possible with most vertical printers, and with the less paste-like ink, the less afiinity it has for fibers and dust, and it does not tend to cake or dry up when the machine is standing idle. The shoe through which the ink is applied to the printing roll acts also as a doctor blade to control the thickness of the ink film, and this is determined by adjusting the spring pin. When the machine is in operation the rotation of the inking roll tends to carry the ink over the shoe, the amount of ink being controlled by the pressure of the shoe against the inking roll, but when the machine is stopped and ink is not being forcibly carried under the shoe in this Way, the shoe presses more tightly against the surface of the inking roll, tending to confine the ink and prevent evaporation. The peristaltic pump is self-priming, which is an important feature.

A defect may from time to time develop in the resilient pump tube 35 or at its terminal connections. If the cover 69 is tight, a pressure may build up in the pump chamber, forcing ink into the top bearing for shaft 11. Also this ink must be cleaned out, usually by flushing the pump cavity with water. In order to signal any leakage of ink and also enable the cavity and the operating parts in the cavity without removing the printer from its mounting, a well 75 is formed in the bottom of the cavity and an escape passage or weep hole 76 is formed from the bottom of this cavity laterally through the plates 9 and 10. Ink that leaks into the cavity fiows into this well and escapes through the weep hole. This prevents any build-up of pressure in the cavity, and more importantly, the escape of ink from the weep hole to this visible area of the machine immediately warns the attendant that the pump requires attention. This construction also allows water or any cleaning fluid used in cleaning up the machine to easily drain away along with the ink which it flushes away, minimizing shut-down time when cleaning is required.

The same arrangement of the shoe bearing against an inking or transfer roll with a groove and inlet and outlet connections along with a peristaltic pump at the end of the roll shaft to provide a self-priming pump may be used in a horizontal position instead of vertical, the only change then necessary being the different positioning of the reservoir. If the shoe is placed in under the ink transfer roll there is little danger of loss of ink by dripping. For a horizontal printer the shoe does not necessarily have to be reversible end-to-end, because right and left no longer become significant, and it makes no difference whether ink enters one end of the shoe or the other.

Also, as indicated above, the same device may be used for the transfer of other fluids, such as mucilage, glue, or other adhesive to a revolving roll corresponding to the inking roll.

While we have shown and described a preferred embodiment of our invention it will be understood that this is by way of illustration and that various changes and modifications may be made within the contemplation of the invention and under the scope of the appended claims.

We claim:

1. An attachment for printing machines and the like for transferring liquid from a reservoir to a rotating workcontacting element having:

(a) a supporting structure having spaced end members forming top and bottom plates,

(b) a roll rotatably supported for rotation about the vertical axes between said end members,

(c) a shoe bearing against the surface of the roll having a concave surface conforming to the curvature of the roll,

(d) said shoe having a vertically-extending groove in the concave face substantially coextensive in length with the axial length of the surface of the roll to which liquid is to be transferred,

(e) means including a pump and tubing for circulating liquid along the groove into one end and out the other so arranged that the groove is normally full of circulating liquid during operation of the unit, and

(f) a reservoir from which the liquid is withdrawn by the pump and into which said liquid is forced from the groove after having transversed the length of the groove,

(g) wherein the rotating roll has a vertical shaft journaled in said end plates, said shaft extending upwardly through the top plate, the said pump being provided on the upper plate, the top of the upper plate having a generally circular cavity therein into which said shaft extends, an eccentric cam on the said shaft in the cavity, a deformable self-restoring tube extending part-way around the wall of the cavity and which is progressively deformed by the rotation of the cam, said cavity tube and eccentric comprising a peristaltic type pump, the end of said tube having connectors thereon externally of the cylindrical cavity, a tube leading from one of the connectors to the reservoir, and the other connector having a tube extending therefrom to the shoe, said tube being interchangeable depending on the direction of rotation of the cam.

2. An attachment for printing machines and the like for transferring liquid from a reservoir to a rotating workcontacting element as defined in claim 1 where the arrangement for circulating liquid through the shoe includes a tube connection at each end of the groove in the shoe and the shoe is reversible end for end, the tube from the pump to the shoe being removably attached to that connection which is at the lower end of the groove, there being a further tube removably attached to that connection at the top of the groove leading back to the reservoir.

3. An attachment for printing machines and the like for transferring liquid from a reservoir to a rotating workcontacting element as defined in claim 2 wherein the connectors on the tube in said cavity are removably received in grooves extending outwardly from the cavity, and a removable cover plate over said cavity and grooves for confining the tube and connectors in said top plate.

4. An attachment for printing machines and the like for transferring liquid from a reservoir to a rotating workcontacting element as defined in claim 1 where the arrangement for circulating liquid through the shoe includes a tube connection at each end of the groove in the shoe and the shoe is reversible end for end, the tube from the pump to the shoe being removably attached to that connection which is at the lower end of the groove, there being a further tube removably attached to that connection at the top of the groove leading back to the reservoir, said reservoir having two tubes extending from near the bottom thereof through the top and having connectors thereon externally of the reservoir, one of which tubes leading from the shoe is selectively attached and to the other end of which the tube leading directly to the pump is attached whereby liquid is always removed from near the bottom of the reservoir and returned to a level near the bottom.

5. An attachment for printing machines and the like for transferring liquid from a reservoir to a rotating workcontacting element as defined in ciaim 1 wherein said cavity has a well in the bottom thereof and an escape passage leading from the well to a visible area of the attaehment, whereby any leakage from the pump enters the well and escapes to signal the existence of pump leakage.

References Cited UNITED STATES PATENTS Von Webern et a1. 101-366 Ball 101-366 Henderson 101-366 X 10 Hirshey 101-366 X Alessi et a1 101-366 X Tyler et al. Judge 118-258 X Van Buskirk 101-366 X Berry 101-169 X ROBERT E. PULFREY, Primary Examiner.

J. R. FISHER, Assistant Examiner. 

